US3784941A

US3784941A - Relay construction

Info

Publication number: US3784941A
Application number: US00232145A
Authority: US
Inventors: Rocher G Du
Original assignee: Essex International Inc
Current assignee: Lear Corp EEDS and Interiors
Priority date: 1972-03-06
Filing date: 1972-03-06
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: CA988564A; JPS54107850U; GB1394041A; DE2310906B2; DE2310906A1; FR2175024A1; IT979558B; JPS4912353A; FR2175024B1

Abstract

A relay construction having an energizable and deenergizable electrical winding operable to effect movements of an armature to and from a switch-closing position and wherein a non-conductive, elastomeric pad is interposed between the switch contacts, the elastomeric pad containing discrete, normally separated, electrically conductive particles dispersed therein in such quantity as to render the pad electrically conductive in response to compression thereof. The pad is mounted in such position as to be compressed in response to movement of the armature toward its switch-closing position. The elastomeric pad may be impregnated with or immersed in a lubricant and may form part of an electrically non-conductive, oil impervious seal or gasket for effect an environmental seal for the operating parts of the relay.

Description

United States Patent 1191 Du Rocher Jan. 8, 1974 RELAY CONSTRUCTION Primary Examiner-l-larold Broome [75] Inventor: Gideon A. Du Rocher, Mt. Clemens, Atmmey john Lemma et Mich. 173] Assignee: Essex International Inc., Port [57] ABSTRACT Wayne, Ind. A relay construction having an energizable and deena ergizable electrical winding operable to effect move- 1972 ments of an armature to and from a switch-closing p0 [21] Appl. No.: 232,145 sition and wherein a non-conductive, elastomeric pad is interposed between the switch contacts, the elastomeric pad containing discrete, normally separated, g fi lg electrically conductive particles dispersed therein in [58] Fieid 5 133. such quantity as to render the pad electrically conductive in response to compression thereof. The pad is 338/100 200/166 166 G mounted in such position as to be compressed in response to movement of the armature toward its [56] References i switch-closing position. The elastomeric pad may be UNITED STATES PATENTS impregnated with or immersed in a lubricant and may 2,951,817 9/1960 Myers 338/100 form part of an electrically non-conductive, oil imper- 3,509.296 4/1970 Harshman at 333/114 vious seal or gasket for effect an environmental seal $235 32 71 5 for the operating parts of the relay.

18 Claims, 10 Drawing Figures ww'av 4 i I' l/52711 vr 4 PATENTEU 8W4 3,784,941

SHEET 2 [IF 2 RELAY CONSTRUCTION A relay of the kind to which the invention relates includes an electrical winding which may be connected to and disconnected from a source of electrical energy so as to energize and deenergize the winding and thereby act on an armature to effect movements of the latter between two positions. In one position of the armature electrical switch contacts are closed, thereby enabling a current path to be established between a source of electrical potential and an instrumentality to be operated. In the other position of the armature the switch contacts are open, thereby breaking the current path to the instrumentality. In such a relay the distance I through which the switch contacts are moved must be sufficient to assure snuffing or extinguishing of any are which occurs between the contacts as they move apart.

The ability of an arc to survive is proportionate to the current values or, stated differently, when a relay controls a current of high value the switch contacts must be capable of substantial movement to assure extinguishing of the arc. The distance the switch contacts must move to assure arc extinguishing requires proportional movement of the armature and, consequently, a proportional size gap in the magnetic flux path of which the armature is a part. The greater the gap in the magnetic flux path, the larger and more expensive must be the electrical winding which effects movements of the armature. Moreover, the greater the distance the armature must move to close or reduce the gap, the greater is its velocity and the greater is the noise of operation of the relay.

A relay constructed in accordance with the invention overcomes the aforementioned problemsvby interposing between the switch contacts of the relay a resilient, compressible pad which is non-conductive in its normal or uncompressed condition, but which contains a plurality of discrete, electrically conductive particles in such quantity that a sufficient number thereof move in engagement with one another in response to compression of the body and establish an electrically conductive path through the body. The resilience of the pad is such that, when the compressive force applied to it is relieved, the particles move out of engagement and render the pad non-conductive, thereby enabling the dielectric material of which the pad is constructed to effect snuffing of any are which otherwise would exist between the switch contacts. As a result of the characteristics of the elastomeric pad, the switch contacts need partake of relatively small movement, the armature need partake of relatively amall movement, and

the size of the electrical winding necessary to effect such movement of the armature can be correspondingly small.

It has been proposed heretofore to immerse relays in oil to assist in are quenching and to reduce the operating noise, but not all such construction have been wholly satisfactory. One of the difficulties encountered with such known relays is that of chemical breakdown or cracking of the oil due to the presence of arcs. A relay constructed according to the invention, however, can be immersed in oil without experiencing such difficulty because at least a portion of whatever acring occurs takes place within the elastomeric pad and, consequently, minimizes chemical reactions in the oil itself.

Another difficulty experienced with oil-immersed relays of conventional construction is that of effecting a seal for the relay housing to prevent the inadvertent escape of the oil. A relay constructed according to one embodiment of the invention overcomes this problem by the provision of an elastomeric, resilient seal or gasket having self-contained, conductive parts by means of which current paths can be established between the interior and the exterior of the relay housing and which also includes a peripheral, compressible sealing bead which may be compressed between the separable com ponents of the relay housing.

A relay constructed according to the invention possesses an outstanding and surprising capacity for accommodating not only high, steady current, but also extremely high transient or inrush currents over sustained periods of time and with remarkably low voltage losses. These characteristics are believed to be due to the presence of a large number of low resistance, conductive particles in the elastomeric switch pad, thereby providing multiple current paths at the interfaces of the switch contacts, coupled with the ability of the elastomer to conform to irregular surfaces at the interfaces and thereby avoid excessively high current density at any current path.

An object of this invention is to provide a relay construction which is capable of effecting switching of high value currents, but which minimizes the distance the switch contacts and the armature must be moved, thereby reducing the size and expense of electrical windings associated with the relay.

Another object of the invention is to provide a relay of the character described wherein the switching means functions also to cushion the movement of the arma ture and eliminate or greatly minimize the noise asso ciated with armature movement.

A further object of the invention is to provide a relay construction which is compatible for use with either oil-immersed relays or relays exposed to air.

Another object of the invention is to provide a switching relay which can accommodate high, steady current values and exceedingly high transient current values.

Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the appended claims and the accompanying drawings, wherein:

FIG. I is a vertical sectional view through a relay constructed in accordance with one embodiment ofthe invention and taken on the line l-I of FIG. 3;

FIG. 2 is a view similar to FIG. I, but rotated through and taken on the line 22 of FIG. 3;

FIG. 3 is a top plan view;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken on the line 5-5 of of FIG. 1;

FIG. 6 is a schematic wiring diagram illustrating the electrical circuitry associated with the relay of FIG. 1;

FIG. 7 is a top plan view of a modified relay;

FIG. 8 is a sectional view taken on the line 8-8 of FIG. 7;

FIG. 9 is a sectional view taken on the line 9-9 of FIG. 8; and

FIG. 10 is an end elevational view.

A relay constructed in accordance with the embodiment of the invention disclosed in FIGS. 1-5 includes a generally cup-shaped, open end housing I having a cylindrical side wall 2 upstanding from a bottom wall 3 and having an outwardly turned rim 4 at its open end. At the center of the bottom wall 3 is an upstanding stop 5. Positioned within the housing 1 is a nonmagnetic bobbin 6 on which is wound an annular winding 7 of magnet wire. The

opposite ends

8 and 9 of the winding are located adjacent the open end of the housing.

The bobbin has a central core 10 within which is slidably accommodated a magnetic armature 11 having a reduced extension 12 at its upper end on which is mounted a phenolic grommet 13 having a peripheral flange 14. The free end of the extension 12 is peened over as at 15 to bear against the grommet 13.

Fitted onto the bobbin core 10 adjacent the open end of the housing 2 is an annular, magnetic member 16 the periphery of which engage the housing wall 2 to form a part of the magnetic flux path. Also fitted onto the bobbin core 10 is an annular, dielectric member 17 of such diameter as to seat upon the rim 4 at the open end of the housing. The member 17 carries on its outer surface an electrically conductive disc 18 adjacent the periphery of the member 17 and a centrally located, annular, conductive member 19 through which the bobbin core 10 extends. Extending radially from the member 19, and diametrically opposite the member 18, is an electrically conductive member 20. Each of the

members

18 and 20 preferably has an opening 21 therein through which the

ends

8 and 9, respectively, of the winding 7 may pass so as to overlie the

member

18 and 20, as is best shown in FIG. 1. The

leads

8 and 9, however, could be soldered or otherwise fixed to the

conductors

18 and 20, if desired.

Overlying and supported on the member 17 is an electrically conductive leaf spring 22 having an opening 23 between its ends for the accommodation of the grommet 13. The spring 22 extends diametrally of the member 17 and normal to the diametral arrangement of the

conductors

18 and 20 so as to avoid engagement therewith. The central portion 24 of the spring 22 is bowed upwardly and bears against the under side of a metallic washer 25 which protects the grommet flange 14 against wear. The spring 22 biases the armature 11 in a direction toward the open end of the housing 1 so that a gap 26 exists between the armature 11 and the stop 5 when the winding 7 is deenergized.

A combined seal and contact carrier 27 overlies the

contacts

18 and 20 and comprises a resilient, generally disc-like web 28 molded of electrically insulating material such as silicone rubber. At the periphery of the web 28 is an annular flange or bead 29 which fits within the rim 4 and bears against the latter and against the periphery of the member 17. The bead 29 extends axially beyond the member 17 for a purpose presently to be explained. The central portion of the web 28 is stepped to form a boot 30 which overlies the armature 11 and its associated parts. The web 28 preferably includes a radially projecting tongue 31 that may be accommodated in a slot 32 formed in the rim 4 of the housing to facilitate proper orientation of the carrier 27 relative to the other parts of the relay.

The web 28 of the carrier 27 is provided with three

openings

33, 34, and 35 each of which receives a contact pad 36. Each pad comprises a molded, resilient, compressible, dielectric substance, such as silicone rubber of the same kind as that forming the web 28, and throughout which a plurality of discrete, electrically conductive particles are dispersed. The size and quantity of the particles are such that they may establish electrically conductive paths through the pads 36. The pads preferably are thicker than the web 28 so as to project beyond both sides of the latter and are either bonded after molding to the edges of the openings or are adhered thereto by being molded in situ. The structural and electrical characteristics of the pads 36 and the manner in which they may be formed are disclosed in U.S. Pat. No. 3,648,002 to which reference may be had for a more detailed description.

The pads 36 are so arranged that, when the contact cartier 27 is assembled with the housing 1, one pad 36 overlies the conductor 18 and the winding lead 8, a second pad overlies the conductor 20 and the winding lead 9, and the third pad overlies one end of the spring 22.

A cover 37 of non-conductive material is provided for the housing 1 and includes a central stepped portion 38 from which extends a peripheral flange 39 that fits snugly within the rim 4 of the housing. Carried by the cover are three

conductive blades

40, 41, and 42 having

legs

43, 44, and 45, respectively, bent to underlie the flange 39. The

legs

43, 44, and 45 overlie the pads 36 in the

respective openings

33, 34 and 35. The cover 37 is maintained assembled with the housing 1 by a plurality of clamp fingers 46 carried by the body wall 2 and bent over the cover flange 39.

Inasmuch as the bead 29 of the carrier 27 projects axially beyond the member 17, it may be engaged with substantial force by the cover flange 39 so as to cause the bead to be compressed and effect a tight seal between the housing and the cover and between the carrier and the member 17. The

contacts

18, 19, and 20 thus are sealed within the housing. Moreover, the legs of the conductive blades 4042 bear forcibly against the pads 36 so as to compress the latter and assure engagement of sufficient conductive particles in each pad to render the latter electrically conductive.

An annular switching member 47 encircles the bobbin core 10 and is interposed between the annular contact 19 and the spring 22. The switching member comprises a pad of resilient, compressible, dielectric material such as silicone rubber throughout which is dispersed a plurality of electrically conductive particles. The particles preferably are copper spheres coated with a low resistance, noble metal such as silver and are of such size and are present in such quantity that, in its uncompressed condition, the pad 47 is nonconductive. When the pad is subjected to compression, however, enough conductive particles move into engagement with one another to establish a plurality of electrically conductive paths through the body between the contact 19 and the spring 22.

FIG. 6 is a schematic wiring diagram ofa typical relay circuit and depicts the blade 42 connected to the positive terminal of a battery or other source of electrical potential and the blade 40 connected to ground potential so that, upon closing of a switch 48, the winding 7 energized via the blade 42, a pad 36, the lead 8, the lead 9, a second pad 36, and the blade 40. The

elements

42, 36, 36 and 40 constitute terminal means for connecting the winding to the energy source. Upon energization of the winding 7, the armature 11 is displaced toward the the stop 5, compressing the switching member 47 between the spring 22 and the conductor 19 and rendering the switching member conductive, thereby establishing an electrically conductive path between the spring 22, the conductor 20, the third pad 36, and the blade 41 which may be connected to an instrumentality such as the winding 49 of a vehicle starter motor, or the like. The

elements

19, 20, 22, 36 and 41 constitute an output or load circuit.

The carrier 27 forms such an effective seal between the housing and the cover that all of the working parts of the relay are completely sealed against the introduction of foreign matter to the interior of the housing. The seal also is so effective that the housing may be filled with oil to obtain the beneficial cooling and noise suppression afforded thereby. It is preferred that sufficient oil be introduced to the housing 1 to occupy the interior of the stepped portion 30 of the carrier 27 and surround the member 47 so as to form an interface between the'switching member 47 and the

members

19 and 22. The oil should be one which is compatible with silicone rubber, and there are many commerically available oils suitable for this purpose. The oil is believed to aid in the quenching of arcs which may occur between the

members

19 and 22 and the switching member 47 and also provides a vehicle by means of which the residue of such arcing may be removed from the vicinity of the pad 47, thereby prolonging the life of the latter.

Itis not essential that oils be contained within the stepped portion 30 of the contact carrier 27. The benefical results of the presence of a lubricant at the switching member 47 can be achieved by either coating or impregnating the body with a machine oil compatible with silicone rubber, and like that used on the ways of a machine tool, or a pasty lubricant such as that manufactured by Fiske Brothers Refining Company, Toledo, Ohio, marketed under the trademark LUBRI PLATE, and designated DS grade No. 0. The paste lubricant should be capable of withstanding 300 F. without vaporization and be compatible with the base silicone resin. Satisfactory results have been obtained using the LUBRIPLATE lubricant referred to above in amounts equal to 0.3 O.6 grams per gram of base silicone resin, excluding the catalyst.

The embodiment of the invention disclosed in FIGS. 7-10 comprises a clapper type relay having an insulating base 50 on which a mounting bracket 51 is secured by screws 52 or the like. Secured to the bracket 51 by one or more screws 53 is one leg 54 of a generally U shaped, magnetic yoke 55 having a second leg 56 which extends through the core 57 of a bobbin 58 formed of insulating material and on which is wound an electrical winding 59. The leg 56 is joined to a third leg 60 which, instead of paralleling the leg 54, extends at an angle thereto for a purpose presently to be explained.

Between the base 50 and the free ends of the

yoke legs

54 and 60 is a magnetic armature 61 which is mounted on a fulcrum 62 supported on the base 50 beneath the leg 54. One end of the armature 61 terminates just short of the leg 60 to form an air gap 63 therebetween and the other end of the armature 61 extends beyond the bracket 51 to overlie a cavity 64 in the base. Fixed to the lower surface of the armature 61 by means ofa screw 65 is a block of insulating material 66. The screw 65 also forms an anchor for one end of a tension spring 67, the opposite end of which is secured to an anchor screw 68 carried by the yoke leg 54.

A blade terminal 69 extends through the base 50 into the cavity 64 and has a leg 70 which seats on the base of the cavity. Atop the leg 70 is a switching member 71, similar to the member 47, comprising a pad of elastomeric, electrically non-conductive material such as sili- 6 cone rubber throughout which is dispersed a quantity of electrically conductive, discrete, metallic particles. The switching member 71 is sandwiched between the leg and an electrically conductive foot member 72 that is carried by the block 66 and is of such size as to be accommodated in the cavity 64.

One end 73 of the winding 59 extends from the latter to the cavity 64 formed in the base 50 and is sand wiched between the pad 71 and the leg 70 of the terminal 69. In engagement with the conductive foot 72 is one end of a conductor 74, the opposite end of which extends to a cavity 75 in the base and is sandwiched between a pad 76, like the pad 36, and a leg 77 ofa blade terminal 78 that is secured to the base and which maintains the pad 76 under sufficient compressive force as to maintain a sufficient number of particles therein in engagement to render the pad conductive. The other end 79 of the winding 59 extends to a cavity 80 in the base and is sandwiched between a pad 81, like the pad 76, and a leg 82 of a blade terminal 83 which extends through the base. The terminal leg 82 maintains the pad 81 under sufficient compression to render it conductive and thereby establish electrical continuity be tween the conductor 79 and the terminal 83.

The terminal 78 is adapted for connection to a source of electrical potential and the terminal 83 is adapted for connection to the opposite terminal of the source or to ground potential. The terminal 69 is adapted for connection to an instrumentality to be operated. The

terminals

78 and 83, together with their associated parts, constitute means for energizing the winding 59 through a switch (not shown) similar to the switch 48, and the

terminals

78 and 69, together with their associated parts, constitute a load circuit of which the switching member 71 is a part.

When the winding 59 is deenerized, the armature 61 assumes the position shown in full lines in FIG. 8 due to the effect of the spring 67. When the winding is energized, however, the armature is caused to rock clockwise about the fulcrum 62, thereby stretching the spring 67 amd compressing the pad 71 so as to render the latter electrically conductive and establish electrical continuity between the

load circuit terminals

78 and 69.

The length of the armature from its free end to the fulcrum 62 is several times the length of the armature from the fulcrum to the connection thereto of the spring 67, thereby providing a substantial multiplica tion of the force applicable to the pad 71 in response to clockwise rocking of the armature. This force is sufficient to assure compression of the pad 71 an amount sufficient to render it electrically conductive and establish an electrical continuity through the load circuit.

The angular relation of the leg 60 is such that, during oscillation of the armature 61 in response to energization and deenergization of the winding 59, the gap 63 is maintained substantially constant.

a The switching member 71 may be impregnated or coated with a lubricant such as those referred to above. Although the member 71 is not immersed in oil, the lubricant nevertheless assists in the quenching of arcs and serves to hold the by-products of arcing in suspension to prolong the life of the switching member.

in each of the disclosed embodiments energization of the winding effects movements of the armature associated therewith to effect compression and closing of the associated switch member. Since the armature acts on a switch member which is composed in part of a re silient, rubbery material, the actuation of the armature virtually is noiseless.

The extent to which either of the switching pads must be compressed to change it from its non-conductive to its conductive condition depends upon several factors, such as its thickness, its durometer hardness, the quantity of particles contained therein, and the size of the particles. In general, the extent to which a pad must be compressed to render it conductive is inversely proportional to its thickness, the concentration of particles, and the durometer hardness of the pad, and is directly proportional to the size of the particles. Nevertheless, the conversion of a pad from non-conductivity to conductivity, and vice-versa, occurs substantially instantaneously. Thus, only a small amount of compression of a switching pad is necessary to render it conductive and a corresponding small amount of expansion of the pad is necessary to render it non-conductive. Consequently, only a corresponding small amount of movement of an armature is necessary to effect proper compression of a pad to render it conductive and a correspondingly small amount of movement of the armature in the reverse direction is necessary to render the pad nonconductive. As soon as the pad is rendered nonconductive, however, no arc can exist inasmuch as the pad then becomes an insulator. Thus, the movement of an armature in a relay according to the invention can be much less than that of conventional relays without risking damage due to arcing. As a consequence, con siderable economies can be achieved with relays of the kind herein disclosed.

The specific force which must be applied to a particular switching

member

47 or 71 to render it electrically conductive can be determined empirically. The force that can be applied on a switching member by a relay armature is directly related to the physical characteristics of the armature and the relay winding and to the electrical characteristics of the relay energizing circuit.

The physical and electrical properties of the particles dispersed throughout the switching pads will vary according to several factors such as the steady and transient current value which must be accommodated by the particles, the force available for compression of the pads, and the resistance of the particles. In general, the particles should constitute between about 78 percent and 93 percent of the weight of a switching pad and may be spherical having a diameter of between about 0.005 and 0.100 inch. The particles preferably comprise copper spheres having an exterior coating of silver. Such particles are less expensive then wholly silver particles, but have substantially the same electrical resistance. Another advantage of silver-coated particles is that the oxidation to which silver is subjected is electrically conductive, rather than non-conductive.

Relays constructed according to the invention have been subjected to extensive testing. The test results indicate uniformly that a relays incorporating a switching member such as those herein disclosed operate much more quietly than conventional relays and are capable of accommodating inrush current values much higher than heretofore thought possible, and without sacrificing the longevity of the relays. This characteristic of relays constructed according to the invention is believed to be due partly to the ability of the resilient pad to conform to surface irregularities which inevitably exist between confronting contacts and thereby provide a relatively large conductive area between such contacts. and partly to the presence of such a large number of conductive particles in the pad to provide a very large number of conductive paths through the pad and thereby avoid the high current density associated with one or only a few current paths.

Although spring devices have been disclosed for the purpose of assuring expansion of the switching

members

47 and 71 and return movement of the respective armatures, the springs could be eliminated in many instances depending on the resilient properties of the switching members. That is, the resilience of a particular switching member could be such that it may expand sufficiently to become non-conductive and return its armature in response to deenergization of the associated winding. If the spring 22 is omitted from the embodiment shown in FIGS. 1-5, some conductive element will have to be substituted therefor so as to bridge the distance between the pad 47 and the associated pad 36. Such a conductor may be a conventional, conductive wire.

The disclosed embodiments are representative of presently preferred forms of the invention, but are intended to be illustrative rather than definitive thereof. The invention is defined in the claims.

What is claimed is:

1. A relay construction comprising an electrically energizable and deenergizable winding; means for connecting and disconnecting said winding to a source of electrical potential; an armature responsive to successive energization and deenergization of said winding to move in opposite directions; load circuit means including first and second spaced apart conductors; normally non-conductive switching means engaging said first and second conductors operable to connect and disconnect said load circuit means to and from a source of electrical potential, said switching means comprising an elastomeric body of dielectric material having a quantity of discrete, electrically conductive particles dispersed therein, the quantity and dispersion of said particles being such that a sufficient number thereof move into engagement with one another in response to compression of said body to establish through said body and between said first and second conductors an electrically conductive path having a resistance corresponding su bstantially to the resistance of said particles; and means mounting said switching means for compression of said body in response to movement of said armature in one direction.

2. The construction set forth in claim 1 wherein said armature is reciprocable.

3. The construction set forth in claim 2 wherein one end of said armature extends beyond a fixed member on which said body is supported, said one end of said armature carrying a part for engaging said body and compressing the latter between said part and said memher.

4. The construction set forth in claim 3 wherein said load circuit means includes a conductor carried by said fixed member and in engagement with said body.

5. The construction set forth in claim 4 wherein one of the conductors of said load circuit means is connected to said means for connecting and disconnecting said winding to its source of electrical potential.

6. The construction set forth in claim 5 wherein said body is sandwiched between said first and second conductors.

7. The construction set forth in claim 6 wherein said one of said conductions is resilient and biases said armature to move in the opposite direction to relieve the compression of said body.

8. The construction set forth in claim 1 wherein the elastomeric dielectric material of said body biases said armature to move in the opposite direction to relieve the compression of said body.

9. The construction set forth in claim 1 wherein said armature is oscillatable.

10. The construction set forth in claim 9 wherein said armature overlies a fixed member on which said body is supported.

11. The construction set forth in claim 9 wherein said armature lies adjacent but spaced from magnetic means to form an air gap, said magnetic means being configured to permit oscillation of said armature and maintain said air gap substantially constant.

12. The construction set forth in claim 1 including spring means acting on said armature and biasing the latter to move in a direction away from said body.

13. The construction set forth in claim 1 wherein said body is coated with a quantity of lubricant in addition to said conductive particles.

14. The construction set forth in claim 1 including a housing within which said winding is enclosed, said housing containing a lubricant.

15. The construction set forth in claim 1 including a housing within which said winding is enclosed, a cover for said housing, and a seal of dielectric material interposed between said cover and said housing, said seal having a plurality of openings therein each of which is filled with a pad of elastomeric, dielectric material containing a plurality of discrete, conductive particles therein in such quantity as to render said pad electrically conductive, said means for connecting and disconnecting said winding to and from its said source including said pads.

16. The construction set forth in clairn 33 including means subjecting each of said pads to compressive force.

17. A relay construction having an energizable and deenergizable winding; an armature responsive to successive energization and deenergization of said winding to move in opposite directions; load circuit means adapted for energization and deenergization in response to movements of said armature, said load circuit means including first and second spaced apart conductors; switching means connected in circuit with said load circuit means; means mounting said switching means in engagement with said first and second conductors and in the path of movement in one direction of said armature for engagement thereby, said switching means comprising a body formed of elastomeric, dielectric material having a plurality of discrete, elec trically conductive particles dispersed therein, the quantity of particles in said body being such that the latter is non-conductive when in a non-compressed condition but is conductive when subjected to compressive force of predetermined magnitude, said winding and said armature being so related to one another that a change in the energized state of said winding effects movement of said armature in said one direction and compression of said body under a force of such magnitude as to render it electrically conductive; and a lubricant other than said conductive particles coating said body.

18. The construction set forth in claim 17 wherein said body is immersed in said lubricant.

* l i =l

Claims

1. A relay construction comprising an electrically energizable and deenergizable winding; means for connecting and disconnecting said winding to a source of electrical potential; an armature responsive to successive energization and deenergization of said winding to move in opposite directions; load circuit means including first and second spaced apart conductors; normally nonconductive switching means engaging said first and second conductors operable to connect and disconnect said load circuit means to and from a source of electrical potential, said switching means comprising an elastomeric body of dielectric material having a quantity of discrete, electrically conductive particles dispersed therein, the quantity and dispersion of said particles being such that a sufficient number thereof move into engagement with one another in response To compression of said body to establish through said body and between said first and second conductors an electrically conductive path having a resistance corresponding substantially to the resistance of said particles; and means mounting said switching means for compression of said body in response to movement of said armature in one direction.

2. The construction set forth in claim 1 wherein said armature is reciprocable.

3. The construction set forth in claim 2 wherein one end of said armature extends beyond a fixed member on which said body is supported, said one end of said armature carrying a part for engaging said body and compressing the latter between said part and said member.

9. The construction set forth in claim 1 wherein said armature is oscillatable.

16. The construction set forth in claim 33 including means subjecting each of said pads to compressive force.

17. A relay construction having an energizable and deenergizable winding; an armature responsive to successive energization and deenergization of said winding to move in opposite directions; load circuit means adapted for energization and deenergization in response to movements of said armature, said load circuit means including first and second spaced apart conductors; switching means connected in circuit with said load circuit means; means mounting said switching means in engagement with said first and second conductors and in the path of movement in one direction of said armature for engagement thereby, said switching means comprising a body formed of elastomeric, dielectric material having a plurality of discrete, electrically conductive particles dispersed therein, the quantity of particles in said body being such that the latter is non-condUctive when in a non-compressed condition but is conductive when subjected to compressive force of predetermined magnitude, said winding and said armature being so related to one another that a change in the energized state of said winding effects movement of said armature in said one direction and compression of said body under a force of such magnitude as to render it electrically conductive; and a lubricant other than said conductive particles coating said body.